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2011. 12. 14. Tobe Laboratory Kitabayashi Kenichi

Synthesis of Dizethrenylacetylene (Candidate for tetraradical ). 2011. 12. 14. Tobe Laboratory Kitabayashi Kenichi. Contents. 1. Introduction - singlet d iradical - zethrene - previous work in our laboratory 2. Purpose of this work - tetraradical

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2011. 12. 14. Tobe Laboratory Kitabayashi Kenichi

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  1. Synthesis of Dizethrenylacetylene (Candidate for tetraradical) 2011. 12. 14. Tobe Laboratory KitabayashiKenichi

  2. Contents 1. Introduction - singlet diradical - zethrene - previous work in our laboratory 2. Purpose of this work - tetraradical - zethrenedimers 3. Experiment and discussion - synthetic route to dizethrenylacetylene - physical properties of dizethrenylbutadiyne 4. Future work and Summary

  3. Singlet Diradical diradical character y y = 0 0 < y < 1 y = 1 closed shell singlet diradical open shell 閉殻 一重項ジラジカル 開殻 y = 0.76 y = 0.81 p-quinodimethane Kubo, T. et al.Angew. Chem. Int. Ed.2005, 44, 6564. Kubo, T. et al. J. Am. Chem. Soc. 2010, 132, 11021.

  4. Moderate Singlet Diradical Zethreneis predicted to exhibit moderate singlet diradical character (y = 0.41)and high two-photon absorption property by computational studies. Nakano, M. et al. Comp. Lett.2007, 3, 333. zethrene (dibenzo[de,mn]tetracene) 7 14 7 7 14 14 HOMO −4.56 eV spin density LUMO −2.34 eV (B3LYP/6-31G*) Tobe, Y. et al. Pure Appl. Chem.2010, 82, 871. It is predicted theoretically that large spin density and frontier orbital coefficients of zethreneare located at the 7,14-positions.

  5. Previous Syntheses of Zethrene Stepwise approach Clar, E. et al. Chem. Ber.1955, 88, 1520. Transannularcyclization (a) Sondheimer, F. et al. Tetrahedron1970, 26, 2141. (b) Staab, H. A. et al. Chem. Ber.1971, 104, 1182.

  6. Synthesis and Physical Properties of3b cross coupling cross coupling transannularcyclization Tobe, Y. et al. Org. Lett.2009,11, 4104. diphenyl- zethrene zethrene 3b rubrene 509GM (604 nm) 1138 GM (604 nm) 492 GM (650 nm) 67GM (612 nm) TPA cross−section diradical character 0.407 0.324 0.432 ̶ GM = 10−50 cm4 s photon−1 molecule−1 TPA cross−section : 二光子吸収断面積

  7. A Stable Tetraradical There is only a weak interaction between both diradical sites. quinoid structure 1.547Å Bertrand, G. et al.Angew. Chem. Int. Ed.2004, 43, 4876. Bertrand, G. et al.Dalton Trans.2008, 4482. ・B2−C2 bond length is a little shorter than normalB−C bond length. ・There is an alternation between slightly shorter and longer in the phenylene ring. 1.411Å 1.383Å 1.404Å

  8. ZethreneDimers (Candidates for tetraradical) ・Dizethrenylacetylene (n = 1) Dizethrenylbutadiyne (n = 2) ・Zethrenylzethrene cumulene Interaction betweendiradicals tert-Butyl groups are omitted for clarity. ・The two zethrene backbones of 4a would be considerably twisted because of strong steric repulsion. ・Since the steric repulsion of the 4b wouldbe small because of the acetylene spacer, two zethrene backbones would adopt a co-planar conformation. Therefore, interaction between two diradicalswould become stronger as expressed by the cumulenic resonance structure.

  9. Retrosynthetic Analyses of ZethreneDimers cross coupling precursors of 4a and 4b homo coupling My first project is to synthesize asymmetric 7,14-dihalozethrenes 7a and 7b.

  10. Synthetic Studies for Asymmetric DisubstitutedZethrenes Transannularcyclization of 1b with IBrand ICl did not give asymmetric 7,14-dihalozethrenes.

  11. Synthetic Route to Dizethrenylacetylene (*) Quast, H. et al.J. Org. Chem. 2008, 73, 4956.

  12. Sonogashira Coupling for Dizethrenylacetylene dizethrenylbutadiyne Attempted Sonogashira coupling of 6 and 5 did not give 4b but 4c which is a homocoupled product of 5a.

  13. UV Spectra and CV of Dizethrenylbutadiyne ・Absorption maximum of 4c was blue shifted compared to that of 3b. ・Small shoulders were observed in the long-wave length region for 4c. UV spectra of 4c (red) and 3b (blue) in CH2Cl2 at 25 ˚C ・Splits of two oxidation waves and reduction waves indicate electron interaction between two zethrene backbones in 4c. Cyclic voltammogram of 4cand 3bin CH2Cl2 (1.0 mM, V vs. Ag/Ag+ in CH2Cl2 containing nBu4NClO4 as a supporting electrolyte, scan rate: 100 mV/s, Fc/Fc+ = 0 V) Eox3 / V Ered2 / V Ered1 / V Eox1 / V Eox2 / V lmax/ nm 561 -1.68 -1.54 +0.21 +0.36 +0.71 578 -1.81 +0.16 +0.65

  14. Future Work ・Synthesis of dizethrenylacetylene by Negishi coupling will be carried out. ・Physical properties of dizethrenylbutadiyne and dizethrenylacetylene will be investigated. ・Zethrenylzethrene will be synthesized.

  15. Summary ・Recently, tetra-tert-butyl-7,14-bis(phenylethynyl)zethrene derivatives whichexhibited high stability, high solubility, and high two-photon absorption property were synthesized. ・Transannularcyclization of the [10]annulene with ICland IBr did not give asymmetric 7,14-dihalozethrenes. ・Attempted Sonogashira coupling of 7-ethynyl-14-(phenylethynyl)zethrene and 7-halo-14-(phenylethynyl)zethrene did not give dizethrenylacetylene but dizethrenylbutadiyne which is a homocoupled product of 7-ethynyl-14-(phenylethynyl)zethrene. ・UV spectrum and Cyclic voltammogram of dizethrenylbutadiyne indicated electron interaction between two zethrene backbones in dizethrenylbutadiyne.

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